Plastic tubing is often connected to laboratory equipment by sliding the tubing over a protruding section of a generally cylindrical connecting portion of the equipment. For example, a connector can have an end formed in the shape of a truncated cone, with the smaller diameter end of the truncated cone proximal to the end of the connector and the larger diameter end of the cone distal to the end of the connector. In this manner, the tubing can be slid onto the connector over the cone. The increasing diameter of the cone encountered by the tubing allows the tubing to gradually expand as it covers the connector, while providing resistance to movement of the tube in the opposite direction.